A document browsed on at a website on the Internet is usually a document described in a markup language such as HTML (Hyper Text Markup language). Although a document described in a markup language is, per se, a text; the user can include character decoration information, such as the font size and colors, and an image, specify their layouts, and set a link to other items in the same document or to other documents and images. The software (computer program) that interprets tag information, included in a document described in such a markup language, and arranges the layout of the document to allow the user to browse its contents is called a browser.
An “onscreen link” defined by the anchor tag is a link to another location in the same document, to another document (including an image), or to a specific function, usually highlighted by an underline, a frame, or a color on the display screen to indicate that the link is set. The user can select this onscreen link to move to another display position or to start a specific function. On a personal computer, the user can select (click) this onscreen link with the use of a pointing device such as a mouse and move to the link destination.
On a mobile phone with the web browsing capability, a document described in a similar markup language can be interpreted and displayed. In addition to HTML described above, compactHTML, XML (eXtensible Markup Language), BML (Broadcast Markup Language), etc. are known as the markup language. The BML is a language used not on the Internet but for data broadcast.
Different documents can also be displayed in the divided areas, called frames, created by dividing the display screen into plural display areas. Patent Document 1 discloses a technique for use on a browser display device, capable of displaying plural frames, to switch the active frame from one frame to another by pressing a single frame switching key.    Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-298543